The objective of the research is to determine the coding of incoming visual information by single units of the primate visual system during eye movements, through two parallel projects. One concerns the psycho-physics of vision during eye movement in humans in which subjects are required to make eye movements across a variety of backgrounds; the effect of eye movements on visual sensitivity are compared with the effect of comparable movements of the background during fixation. The other is a coordinated neurophysiological investigation of single unit activity both in the visual system of monkeys trained to eye movements, and in semi-acute, anesthetized monkeys with immobilized eyes. Detailed receptive field analysis in the anesthetized animal will be compared to neuronal behavior in the alert performing monkey.